<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>05流程控制</title>
</head>
<body>
<script>
    //1.顺序结构
    console.log(1);
    console.log(2);
    console.log(3);
    //2.分支结构
    let username = '露娜';
    if(!username){//若用户名为空字符串,转为布尔是false,!false为true,走分支1
        alert('用户名不能为空!');
    }else{
        alert('欢迎'+username+'回来!');
    }
    //3.选择分支
    let gender = 1;
    switch (gender){
        case 1:
            console.log('先生');break;
        case 0:
            console.log('女士');break;
        default:
            console.log('保密');
    }
    //4.循环结构
    let names = ['张三','李四','王五','赵六','钱七'];
    for(let i=0;i<names.length;i++){
        console.log(names[i]);
    }
    //增强for循环 names表示当前要遍历的集合/数组
    //let n表示本轮遍历到的元素
    for(let n of names){
        console.log(n);
    }
</script>
</body>
</html>